Celestia and WWT are two different programs. Celestia is a 3D model of the universe and WWT is a series of images from actual telescopes ala NASA's World Wind.
WWT doesn't take you to a 3D location like Celestia, but zooms in on actual telescope imagery. I have both.
-S
PS. In case you don't know what World Wind is -
http://worldwind.arc.nasa.gov/